The invention relates to a device with a flat component made of fiber-reinforced synthetic material and an end power induction unit, in particular at a leaf spring or transverse link for motor vehicles. Various elements of the device cooperate to reduce certain loads and stresses typically imposed on leaf springs of this type.
In generic devices, such as a leaf spring made of fiber-reinforced synthetic material, particular attention must be paid to the power induction into the component, because damage due to excessive bending moments or shear stress originates or appears almost regularly at a power induction unit. Where a leaf spring is installed transversally in a motor vehicle, it must absorb both vertical forces due to the static and dynamic axle load and high lateral forces while taking curves. While braking the vehicle, it is still possible for significant longitudinal forces or torsion couples to appear. In this, the vertical forces have a perendicular effect on the directed fiber layers of the leaf spring, while the lateral forces are parallel, and thus in the fiber direction. Particularly high bending moments and shear stress appear while taking curves because here great vertical forces from the dynamic axle weight shift is added to the great amount of lateral force. These high strains can result in excessive stress, especially in the area of the power induction unit; damage that can occur includes separation of the upper and lower levels of directed fibers, fiber tears on these levels and deformations on the component. The object of the invention is to reduce the stress in the area of the power induction unit for the generic device, using simple means.
This object is accomplished by features of the invention described herein. A feature of the invention is the application of force at the power induction unit asymmetrically to the fiber levels. This permits absorption of the component or leaf spring end in the power induction unit such that the latter experiences a moment of torsion from the lateral forces, which is directed against the vertical forces of the axle weight. The result is a considerable reduction in bending stresses in the area of the power induction unit, and a reduction in shear stress. The definition of the length of the component or of the leaf spring end beyond the point of application of force in the power induction unit means an equivalent decrease in stress and a reduction of shear stress for lateral forces acting in the opposite direction.
As described in detail hereinafter the power induction unit and the end portion of the leaf spring are specially configured to insure the spring is properly retained and the power is absorbed as desired. In particular, wedge-shaped design of the end portion of the component has proven to be particularly advantageous and capable of bearing stress.
Insofar as additional, one-sided, relatively high torsion couples act on the component, as sometimes happens, for example, with a wheel-drive leaf spring while braking a vehicle, the point of application of force on the power induction unit can be arranged asymmetrically to the spring itself. The power induction unit is formed of two separate parts with clamping means involving little or no invasive elements to the fiber material. The arrangement of the screws or bolts about the periphery of the end portion means that the effective cross section of the component or of the leaf spring is fully preserved.
The above has been a brief description of deficiencies in the prior art and advantages of the invention. An embodiment of the invention is described below in greater detail.